How to handle "Nullable value type may be null" (for TimeSpan) inside the sum() methode?-CodePudding

In my Asp.net core project, I need to check for null TimeSpan properties. This is my method:

 return result.Include(e => e.Episodes).AsEnumerable().Select(c => new ShowListCoursesViewModel()
            {
                CourseId = c.CourseId,
                CourseImageName = c.CourseImageName,
                CoursePrice = Convert.ToDecimal(c.CoursePrice),
                CourseTitle = c.CopurseTitle,
                CourseTotalTime = new TimeSpan(c.Episodes.Sum(t => t.EpisodeTimeLength.Value.Ticks) )
            }).Skip(skip).Take(take).OrderByDescending(d => d.CoursePrice).ToList();

It's showing a green squiggle under the t.EpisodeTimeLength and saying:

Nullable value type may be null.

My CourseTotalTime property is nullable and also the EpisodeTimeLength is nullable too.

How can I interpret null values of EpisodeTimeLength as 00:00:00 in the Sum? Example: [null, 01:00:00, 01:00:00] should yield 02:00:00 in CourseTotaltime.

CodePudding user response：

You can exclude null values with Where before the Sum:

CourseTotalTime = new TimeSpan(
    c.Episodes
        .Where(t => t.EpisodeTimeLength.HasValue)
        .Sum(t => t.EpisodeTimeLength.Value.Ticks))

Alternatively, you can specify a default value to use when t.EpisodeTimeLength is null:

CourseTotalTime = new TimeSpan(
    c.Episodes
        .Sum(t => (t.EpisodeTimeLength ?? TimeSpan.Zero).Ticks))

This makes use of the null-coalescing operator.

Demonstration of both approaches